Currently, the establishment of a telephone call between a mobile cellular phone user and a telephone number or internal extension that exist within an internal private branch exchange (PBX) is done by directly contacting the destination through the public switch telephone network for connection. In cases where the target destination is overseas, the costs of making such calls are high.
To address the cost issue, existing solutions use e.g. Voice over Internet Protocol (VoIP) integrated with the PBX network to reduce the cost of international calling by transmitting the calls over the Internet. However, this method only allows calls to be made using special Internet Protocol (IP) phones or computer-based phones (softphones), thus typically restricting the user to making calls within the office environment only. When a user is on the move outside the office environment, VoIP calls made from the mobile phone are implemented and executed externally from any existing PBX network, i.e. such calls are subjected to conventional charging arrangements associated with the relevant mobile network(s) and/or VoIP gateways.
Example embodiments of the present invention seek to address one or more of the above problems identified by the inventors.